Methods for obtaining highly purified Langerhans Cells (LC) directly from epidermis or by directed differentiation of CD34+ progenitor cells are proposed. Development and commercialization of products for LC purification will aid basic research on the role of LC in skin diseases such as psoriasis, Kaposi's sarcoma and atopic dermatitis. The therapeutic goal of the work is to develop a method of growing LC from bone marrow, and using the LC as an antigen presenting cell line for cytotoxic CD8+ T cells. We propose applying this system in an immunotherapeutic approach to AIDS, based on the use of HIV-associated antigens in the LC culture system. The system may provide a generally applicable method for generation of antigen specific cytotoxic T cells.